Considerations in High-Speed Tilting -Pad Journal Bearings of Unspecific Geometry

摘要

The objective of this study consists of comparing two solutions of hydrodynamic thin tilting-pad journal bearings: 1. the first one is a bearing which has the tilting-pads arranged in a regular geometry (each pad is characterized by the values of clearance and preload factor -the same for all the tilting-pads); 2. the other one benefits by a special geometry: the pads are arranged two-with-three (two of them work for one value of clearance and a preload factor while the others three are arranged for another value for clearance and preload factor); This comparison has been suggested by the necessity of choosing the optimal solution in high-speed bearings (20000 rpm or even more). In order to employ optimization techniques to design bearing solution and to determine when it is right to use tilting-pad journal bearings, it will also be presented a summary process of bearing selection taking into account some suitable types of bearings with fixed geometry and others with variable geometry (with tilting-pads) which have their particular strong points (see fig. la-e) The computation's results and conclusions, which this study presents, are illustrated and confirmed by the development and operation (over 20000 h) of such bearings as they are described.